Parking brake control with transmission interlock

ABSTRACT

A control system for a vehicle having a parking brake and a transmission is provided with means cooperating with the transmission controls to bias the transmission into a neutral condition when the parking brake is applied. The cooperating control means coact to shift the transmission to a neutral position if the parking brake is applied with the transmission in either a forward or reverse drive condition. A resilient biasing means is employed to provide a manual override to enable the transmission to be manually held in an operating condition with the parking brake engaged.

United States Patent [191 Anderson et al.

[ PARKING BRAKE CONTROL WITH TRANSMISSION INTERLOCK [75] Inventors:Rodney H. Anderson, Naperville;

Ralph R. Day, Aurora, both of 111.

[73] Assignee: Caterpillar Tractor Co., Peoria, 111.

22 Filed: June 14, 1971 211 Appl.No.: 152,712 I 52 u.s.c|. ..-..l......192/4c, 74/480 R, 188/729 51 Int. Cl. ..B60k 29/02 [58] Field ofSearch 192/4 B, 4 c, 4 A

[56] References Cited UNITED STATES PATENTS 3,390,523 7/1968 Heidernannetal. ..192/4BX 3,645,368 2/1972 Blaavw ..192 4c 3,349,860 10/1967Ross... .....l92/4BX 2,964,135- 12/1960 Sand ..192/4AX 11] 3,729,074 451Apr 24, 1 97 3 1,999,284 4/1935 Colvin 192/109 A X 3,498,425 3/1970Takada ..192/4 A 3,539,040 1 1/1970 Edwards ....192/4 B 3,618,71811/1971 Blaavw ..192/4 B Primary Examiner-Benjamin W. WycheAttorneyChar1es M. Fryer et a1.

[57] ABSTRACT 2 Claims, 2 Drawing Figures Patented April .24, 1973 2Sheets-Sheet 1 INVENTORS RODNEY H. ANDERSON RALPH R. DAY

Patented April 24, 1973. 3,729,074

2 Sheets-Sheet 2 INVENTORS RODNEY H ANDERSON RALPH R. DAY

W 91;)" 7) A'munwcm PARKING BRAKE CONTROL WITH TRANSMISSION INTERLOCKBACKGROUND OF THE INVENTION tion of the vehicle parking brake, andincluding means for manual override to hold the transmission in whilethe brake is engaged.

It is customary in vehicle designs to provide a parking brake which alsofunctions as an emergency brake. Many of the present day vehicles haveengines of sufficient torque to overpower the parking brake. To preventthis from occurring, some vehicles are provided with parking brakecontrols which coact with the transmission controls to shift thetransmission to neutral when the parking brake is applied. Examples ofsuch prior known systems are shown in the following U.S. patents: (a)U.S. Pat. No. 3,480,120 issued Nov. 25, 1969; (b) U.S. Pat. No.3,050,165 issued Aug. 21, 1962; and (c) U.S. Pat. No. 3,181,667 issuedMay 4, 1965.

The arrangements to date generally effect positive interlock so that theparking brake control must be shifted to the release position before thetransmission can be shifted to an operating position. Although thisfeature is desirable, there are some emergency situations where it isbeneficial to .be able to engage the transmission without releasing theparking brake mechanism. One such instance is when the parking brake isused as an emergency brake should a failure occur in the primary brakingsystem. If the parking brake is not'properly adjusted, or if the vehicleis negotiating adverse grades, the parking brake may not have sufficientbraking capacity to stop the machine and the operator may instinctivelytry to shift the transmission to a reverse gear to help control thevehicle. With the currently commercially available arrangegear ment, thetransmission cannot be engagedwhile the parking brake is applied andthus the braking action afforded by the transmission reversal cannot beutilized concurrently with the parking brake for such emergencysituations.

SUMMARY AND OBJECTS OF THIS INVENTION ment to provide a means to biasthe transmission of a vehicle into neutral while the parking brake isengaged to prevent the machine from being driven inadvertently with theparking brake engaged.

Another object of this invention is to provide a means to automaticallyshift a vehicle transmission to neutral when the parking brake isapplied should the transmission be in an operating position at the timethe parking brake is applied.

It is a further object of this invention to incorporate a resilientmeans to allow the operator to manually force and hold the transmissionin an operating position while the parking brake is applied.

BRIEF DESCRIPTION OF THE DRAWINGS Other objects of this invention willbecome apparent from the following description and accompanying drawingswherein:

FIG. 1 is a side elevational view of a vehicle employing a preferredembodiment of the present invention with portions broken away to showdetails;

FIG. 2 is a detailed view of the preferred embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to FIG. 11, theinvention is illustrated as being incorporated in a four-wheeledarticulated vehicle which has a front frame 11 and a rear frame 12connected together at 13 for pivotal movement about a substantiallyvertical pivot axis. The front frame 11 carries an engine 14 which isdrivingly connected to a transmission 16 through a torque converter 17.The

transmission 16 is of conventional construction wherein the speeds anddirection are changed by a hydraulic control system in a conventionalmanner. The transmission 16 has interconnected output shafts 18 and 19which are connected to front and rear drive wheels 21 and 22 throughdrive axles 23 and 24. The output shaft 19 carries a brake disc 26 of aparking brake apparatus 27. Since the output shaft 18 and 19 areinterconnected for rotation with one another, application of the parkingbrake 27 is effective to stop rotation of all four wheels of thevehicle.

As more clearly shown on FIG. 2, the parking brake apparatus 27comprises a mounting bracket 28 secured to the rear of a transmissionhousing 29. A pair of levers 31 and 32 pivotally attached to the bracket28 at 33 and 34 carry conventional brake pads 36 whereby pivotalmovement of levers 31 and 32 toward one another cause the pads 36 toclamp against the disc 26 to stop rotation thereof.

The parking brake apparatus 27 is operated through a manual controllinkage which includes a manuallyoperated lever 37 pivotally attached at38 to a housing 39. A link 41 attaches to lever 37 at 42 and at 43 to arod 44 which is reciprocally contained inside the housing 39. Thehousing 39 is provided with a slot 46 for guiding the movement of thelower end of link 41 when the lever is pivoted about pivot 38. The rod44 extends downwardly through the housing and projects from the bottomthereof terminating with a connection to a cross-bar 47.

The parking brake control linkage also includes a push-pull cable 48having one end secured to the housing 39 and the other end secured tothe bracket 28 in a conventional manner. One end of a central rod member49 of the push-pull cable 48 is pivotally attached to the cross-bar 47while the other end is pivotally attached to an arm 51 of a bellcrank 52which is pivotally secured at 53 to the lower end of lever 32. Anadjustable link 54 is pivotally connected to the lower end of lever 31at 56 and at 57 to a second arm 58 of bellcrank 52.

To apply the brake, the lever 37 is pivoted counterclockwise about itspivot 38 causing link 41 to move the rod 44 upward. The upward movementof rod 44 pulls the central rod member 49 through the push-pull cable 48and thereby rotates bellcrank 52 counterclockwise causing the levers 31and 32 to move the brake pads 36 toward one another and clamp againstthe disc 26 to stop rotation thereof.

The transmission control means comprises a manually-operated linkage 59for shifting the hydraulic control valves (not shown) which are integralparts of the transmission 16. The control linkage includes a manualshift lever 61 mounted adjacent a steering column 62 and a lever 63secured to a shaft 64 which extends through the transmission housing 29.The opposite end of shaft 64 is operatively connected to theinternally-mounted control valve. Manipulation of shift lever 61 resultsin pivotal movement of an end 66 of lever 63 to one of the threepositions indicated by the letters F, N and R which correspond toforward, neutral, and reverse conditions of the transmission.

A second push-pull cable 68 has one end secured to the bottom of housing39 and the other end secured to a bracket 69 fastened to thetransmission housing 29. A first end of the central rod 71 of cable 68is attached at ,72 to cross-bar 47 while a second end 73 extends througha lever 74 which is pivotally mounted to the housing 29 at 76. Thesecond end 73 of rod 71 terminates with a nut 77 which retains a coilspring 78 disposed between the lever 74 and the nut 77. The lever 74includes a V-shaped notch 79 defined by two converging caming surfaces81 and 82 which cooperate with an abutment portion 83 of lever 63 of thetransmission control linkage 59 to bias the lever 63 to and retain it inthe neutral position as shown when the parking brake is engaged. Whenthe lever 63 is in the position shown, actuation of the parking brakelinkage to apply the brake will cause the central rod 71 of cable 68 tobe pulled through the cable 68 thereby causing the spring 78 to exert aforce on the lever 74 which rotates clockwise about pivot 76 until theV-shaped notch 79 engages the abutment portion 83 of lever 63 and thetransmission control linkage will be restrained in the neutral positionuntil the parking brake is released. Thus, inadvertent operation of thevehicle with the parking brake applied will be prevented.

if the transmission control linkage and lever 63 is in either theforward or reverse positions indicated by F and R and the parking brakeis applied, one of the caming surfaces 81 or 82 will engage thecooperating abutment portion 83 of lever 63 and force the transmissioncontrol linkage into its neutral position as lever 74 is pivotedclockwise about pivot 76. When the lever 74 is in the position shown onFIG. 2, the transmission control linkage and lever 63 can be shifted toeither of the drive establishing positions F or R without interference.

Under normal circumstances, the above-described Y mechanism is effectiveto prevent the vehicle from being inadvertently operated with theparking brake applied. However, in an emergency situation such as if theprimary brakes have failed, it may be desirable to utilize the brakingaction afforded by the engine or the reversal of the transmission inconjunction with the braking action of the parking brake apparatus tocontrol the vehicle. In this situation the operator can manually forcethe transmission control linkage to an operating position whereby thelever 74 is forced counterclockwise against the bias of spring 78. Whenthe emergency situation is passed, the operator releases the shift lever61 and the spring 78 will again force the lever 74 clockwise to shiftthe transmission lever 63 to the neutral position.

What is claimed is:

1. A control system for operatively interconnecting a parking brakecontrol having an actuated position and a release position, and atransmission control shiftable between a neutral, and forward andreverse drive positions; said control system comprising:

a brake actuating control lever;

a transmission shift member;

means operatively connected to said brake control lever and operativewhen said brake control lever is in said actuated position to force saidshift lever to a neutral position;

said means to force said shift member comprises camming means includingcamming surfaces defined by a substantially V-shaped notch carried on alever mounted adjacent to said shift member for operative engagementwith an arm extending from said shift member into the space between saidcamming surfaces;

resilient means connecting said brake control lever to said cam lever;

said resilient means comprises a flexible cable, and,

a compression spring mounted on said cable between a stop at the endthereof and said lever so that said resilient means functions as a lostmotion connection.

2. A control system for operatively interconnecting a parking brakecontrol having an actuated position and a release position, and atransmission control shiftable between a neutral, and forward andreverse drive positions; said control system comprising:

a brake actuating control lever;

a transmission shift member;

means operatively connected to said brake control lever and operativewhen said brake control lever is in said actuated position to force saidshift lever to a neutral position;

said means comprising cam means carried on a pivotal arm;

a resilient cable including a compression spring mounted on the end ofsaid cable between a stop member and said pivotal arm connecting saidcontrol lever to said arm; and,

an arm extending from said shift member for engagement with said cammeans.

1. A control system for operatively interconnecting a parking brakecontrol having an actuated position and a release position, and atransmission control shiftable between a neutral, and forward andreverse drive positions; said control system comprising: a brakeactuating control lever; a transmission shift member; means operativelyconnected to said brake control lever and operative when said brakecontrol lever is in said actuated position to force said shift lever toa neutral position; said means to force said shift member comPrisescamming means including camming surfaces defined by a substantiallyV-shaped notch carried on a lever mounted adjacent to said shift memberfor operative engagement with an arm extending from said shift memberinto the space between said camming surfaces; resilient means connectingsaid brake control lever to said cam lever; said resilient meanscomprises a flexible cable, and, a compression spring mounted on saidcable between a stop at the end thereof and said lever so that saidresilient means functions as a lost motion connection.
 2. A controlsystem for operatively interconnecting a parking brake control having anactuated position and a release position, and a transmission controlshiftable between a neutral, and forward and reverse drive positions;said control system comprising: a brake actuating control lever; atransmission shift member; means operatively connected to said brakecontrol lever and operative when said brake control lever is in saidactuated position to force said shift lever to a neutral position; saidmeans comprising cam means carried on a pivotal arm; a resilient cableincluding a compression spring mounted on the end of said cable betweena stop member and said pivotal arm connecting said control lever to saidarm; and, an arm extending from said shift member for engagement withsaid cam means.